Thymic neuroendocrine carcinoma and thymoma are both associated with increased risk of extrathymic malignancy: A 20-year review of a single institution

Background Thymoma has been reported to have increased risk of extrathymic malignancy; thymic carcinoma, however, has not been validated of this association. We retrospectively assessed the incidence of additional malignancy among patients with thymoma and thymic carcinoma, and compared it with that of other solid organ cancers. Methods We reviewed the medical records between the years of 1988 and 2008 of 213 patients, including 131 with thymoma and 82 with thymic carcinoma. The overall incidence of additional malignancy in patients with thymic epithelial tumors, lung cancer, hepatocellular carcinoma, colorectal cancer, breast cancer, and cervical cancer between 2003 and 2008 in our institution was also computed. Results The incidence of extrathymic malignancy in patients with thymic epithelial tumors was 12.2% (16 of 131) for thymoma and 12.2% (10 of 82) for thymic carcinoma. The overall incidence of additional malignancy between 2003 and 2008 was significantly higher among patients with thymoma than among patients with hepatocellular carcinoma, colorectal cancer, breast cancer, and cervical cancer (p = 0.017, 0.022, 0.009, and 0.018, respectively). In thymic carcinoma, the likelihood of developing extrathymic malignancy was significantly higher among patients with neuroendocrine carcinoma than among patients with other thymic carcinomas (p = 0.000). Extrathymic neoplasm did not pose a significant influence on the overall survival of patients with thymoma (p = 0.085) and thymic carcinoma (p = 0.814). Conclusions Our data demonstrated the increased risk of extrathymic malignancies among patient with thymoma. In thymic carcinoma, this association mainly occurred in patients with neuroendocrine carcinoma. Actions for early detection of extrathymic malignancy should be considered for patients with these thymic epithelial tumors.